''It is extremely important that Israel exercise restraint in its acts of self defence,'' she told reporters travelling with US President George W Bush in Germany yesterday.

Her comments, at a hastily arranged briefing, reflected a sharper focus on Israel than statements from Bush earlier, who said Israel has a right to defend itself with its attacks in Lebanon but that it should not weaken the Lebanese government.

Rice said the message was being sent through numerous diplomatic channels and added: ''I think they understand the need to exercise restraint.'' Israel struck Beirut airport and military airbases and blockaded Lebanese ports on Thursday, intensifying reprisals that have killed 55 civilians in Lebanon since Hizbollah captured two Israeli soldiers a day earlier.

Asked in a CNN interview about Rice's call, Israel's ambassador to the US said Israel had exercised restraint since its 2000 withdrawal from Lebanon and believed its military offensive was now the right way to deal with Hizbollah.

Ambassador Daniel Ayalon said: ''I think they (Hizbollah) misinterpreted our restraint for the last six years.'' ''If we do not want to see further escalation, deterioration, violence, this is the time to stop Hizbollah and what we are doing is the most effective (way) to stop them.'' Bush's national security adviser, Stephen Hadley, said he and Rice had spoken to Israeli officials and received assurances Israel's focus was on Hizbollah, not the Lebanese government.

He added that the officials said ''the actions they are going to take are going to deal with Hizbollah, will be done in such a way to try and minimize collateral and civilian casualties, recognizing this is difficult because Hizbollah has put targets in civilian areas''.

Rice said Syria had been ''sheltering the people who have been perpetrating these acts'' against Israel, including launching rocket attacks into northern Israel and abducting Israeli soldiers.

''Syria needs to act responsibly and stop the use of its territory for these kinds of activities. They need to bring all pressure on those that it is harbouring to stop this and to return these soldiers and to allow the situation to be de-escalated,'' Rice said.

She said the United States supported a three-person UN team being sent to the region to try to defuse the crisis on the instigation of UN Secretary-General Kofi Annan.

Asked if there was a danger of the area slipping into war, Rice said: ''I think it doesn't help to speculate about kind of apocalyptic scenarios. What we have to do is work day by day, hour by hour. That's what we're doing, and that's what a lot of others are doing.''